Balance for watch movements



April 1, 1930. B. J. BATES 1,752,773v

BALANCE FOR WATCH MOVEMENTS Filed Aug. 1, 1927 2 I 9 7 3. .4 II I I INVENTOR B THELIBATES.

ATTORN EY Patented Apr. 1, 1930 UNITED STATES PATENT OFFICE BETI-IEL J'. BATES, OF CLEVELAND, OHIO, ASSIGNOR OF ONE-HALF TO ALBERT S. GREGG, F CLEVELAND, OHIO BALANCE FOR WATCH MOVEMENTS Application filed August 1, 1927. Serial No. 209,845.

This invention relates to balances for watch movements, and particularly to the means for connecting the hair spring to the collet of the balance.

It is customary to connectthe spring to the collet by means of pins, and this has many disadvantages or objectionable features, particularly in connecting and disconnecting the spring.

By means of the present invention these objections are avoided, and the spring can readily be disconnected and changed, and re placed in position on the balance. A new spring can easily be put in place when desired. is These results are procured by making a slot adjacent to the flat wall of a D shaped counterbore in the collet and providing the inner end of the spring with a hook or bend which can be dropped into the slot in setting the spring in place, and which can be simply lifted out of the slot when the spring is removed, without disconnecting the collet in either instance. The slot connection also permits the spring to assume its proper level or position, which permits it to coil or uncoil more freely and it is not liable to be cramped or twisted or thrown out of line or level by temperature changes; nor is the spring apt to be broken by jars or jolts.

Further advantages of the invention will be apparent from the following description and the accompanying drawings in which Fig. 1 is a plan of the balance wheel and spring. Fig. 2 is a section on the line 22 of Fig. 1. Fig. 3 is a perspective of the collet.

In the drawings 1 is the hairspring and 2 is the overcoil thereof fastened at its outer end to a stud 10 in the usual manner The inner end of the spring is bent as indicated at 8 to form a hook which fits in a slot 9 in a collet 7 frictionally secured to the hub 4 on the staff 5, which hub carries the balance wheel 3 by means of the arms 6. The coil is spaced from the stafl, to allow the end of the hook 8 on the spring to enter between the collet and the staff. The ends of the flange of the collet acent tie slot 9 are widened or thickened and flattened on the inside, as indicated at 7 The purpose of this is to permit the use of a bend or hook 8 of sufficient and suitable size,

and the flattened faces on the inside confine the end of the hook to avoid movement or 31a of the end of the hair s rim 1 y P c There must be absolutely no play or variation at said end, otherwise it would be impossible to properly regulate the time piece. lVhen the hook of the spring is in place in the slot the spring may rise and fall or seek its level, but by reason of the engagement of the hook in the slot the pressure of the spring will be applied to the collet in both directions, as it coils and uncoils.

It will be noted that the spring can be readily detached by lifting its hooked end out of the slot, or it can be quickly connected by slipping it into the slot.

This

avoids many of the objections and difficulties incident to pinning the spring to the collet, and the collet does not have to be disconnected for either of these operations.

I claim:

nature.

BETHEL J. BATES. 

